Method of treating oil and gas wells



Jan. 14, 1941. w, M. JARRELL 'METHOD OF' TREATING OL AND GAS WELLS 20,1958 2 Sheets-Sheet 1 Filed Dec.

Survol/vbo@ .JARRELL Jan. 14, 1941. w- M. JARRELL METHOD OF TREATING OILAND GAS WELLS Filed Dec. 20, 1938 2 Sheets-Sheet 2 /nuefnorc VV.VLCFARRE LL @Morm Patented Jan. 14, 1941 UNITED STATES PATENT 'oi-FICE 3Claims.

The invention relates to a means and method of treating oil and gasWells to remove accumulations ofA parain or asphalt, or soft shale, orshale muck or rotary mud therein.

The present invention relates generally to that disclosed in myco-pending application, ASerial No. 87,502, led June 26, 1936, for aMeans and method of treating wells, theY present invention being morespecic as to details of the method posed formation and for distancesback into the A formation between the interstices of the sand particlesof the'formation and deposits of shale muck, if shale is present in ornear the voil formation and where water contactsV such shale, alsodeposits formed from surface water entering into the well, and rotarymud left from drilling. Such deposits also occur on the well tubing,casing and liner, so that it becomes necessary from time to time toremovethis coating of paramn, asphalt gum, shale muck and rotary mud.

It is an object of the invention to provide a 80 means and methodwhereby the parafnn, asphalt, mud and muck accumulations in the wellbore arev dislodged and disintegrated and suspended by the agitation ofa chemical reaction and are Y then forced upwardly in the well bore tobecome intermixed with water and oil sdas to form an emulsion from whichthe parailin, asphalt, mud

and` muck will not recongeal. 'I'his is accomplished by the fact thatsmall particles of the chemical travel upward into the oil and water 40and spend'the force oftheir reaction in that body ofoil and water in thewell bore, maintaining a oonstant'heat far above the congealing point ofany of the substances dislodged.

Another object of the invention is to form an emulsion in a well bore byheating the paramn and muck in the well by a heating reaction ofchemical. caustic soda and watensg that the mixture of paraln, asphalt,muck and^mud, steam and gas generated by the chemical will provide acontinuous reaction to agitate the smaller particles of the chemicalwithin the well bore so as to develop the entire strength of thechemical and to form an emulsion with an oil and water deposit in thewell bore.

Still another Vobject of the invention is to provide a container f orchemical and caustic soda to be dropped into a well bore which containeris composed of fabric which will be consumed by the reaction.

Still another object of the invention is to provide 5 a convectioncirculation in a well bore due to an exothermic heat reaction which willdisintegrate the muck on the face of the formation and entrap, whilemaintaining a constant heat far above the congealing point, suchdisintegrated paraiiln 10 asphalt, mud or muck being moved up into thewell bore by the liberation of gas from the chemical reaction, in a bodyof oil and water so that it can not recongeal and may be removed fromthe Well bore by swabbing or otherwise.

Other and further objects of the invention will be readily apparent whenthe following description is considered in connection with theaccompanying drawings wherein:

Fig. 1 is a vertical section wherein the fabric 20 container for thechemical and caustic soda is' shown in elevation with certainr partsbroken away to illustrate the contents thereof. f

Fig. 2 is a vertical sectional view showing diagrammatically a well borewhere a. cavity has -25 been formed and upon the walls of which adeposit of paraln, asphalt, muck or mud has accumulated and is to beremoved and shows the deposited water and the fabric container or chargeof chemical being dropped into the well 30 bore. y

Fig. 3 is a view similar toFig. 1 but showing the reactionjas havingbeen 4initiated and the convection circulation established to melt anddislodge the muck and accumulation from the 35 formation.

Fig. 4 shows the next step .of the method wherein the accumulation"formed is being'reinov'ed' by a swabbing action.

Fig.'v 5 shows the well after vtheemulsion and 40H' l other materialshave beenreinoved therefrom and wherein a vacuum has beenf'createdinjtheulell while the well 'is empty'sojas to -draw into the Y well' anywater which iiiiglitbe" remaining in the l formation or near the surfaceof theformation, 45 and such vacuum tends to initiate a flow of oil,back into the well. l

Fig. 6 shows :a view wherein a well containing a liner and strainer isbeing treated while a pressure is being maintained thereon.4

Fig. '7 shows another form wherein -a tubing and strainer remain in thewell and thesuction. is applied thru the tubing. l

In Fig. 1 a tube 2 has been illustrated which is preferably. of metaland is provided with a 55 cover 3. This tube 2 is arranged to receive afabric container 4 which is in the nature of a fabric covering for abody of chemical and acid 5.

This fabric container 4 can be made of any suit- 5 able fabric but inactual practice it has been found that either silk or wool is preferablebecause these fabrics will be consumed by the reaction of the chemicaland caustic soda. The chemical is usually aluminum castings of aluminumsand, aluminum dross, oil and the caustic soda may bel flaked causticsoda. These materials may be intimately mixed together and it has beenfound in actual practice that, by coating'the particles of aluminum andchemical with a small quantity of heavy lubricating oil that theabsorption of moisture will be prevented. The caustic is thus preventedfrom attacking the aluminum prior to the addition of water so that thecomplete charge may be readily mixed and stored for long periods of timewithout deterioration.

The tube will be transported to the well and when it is to be used thefabric container 4 will be removed andthe fabric container and charge ofmaterial introduced into the well bore.

Fig. 2 shows a diagrammatic arrangement of a well I which is providedwith a casing II. This casing penetrates the earth formation I2 to theelevation of a producing formation I3. The well cavity is illustrated atI4 and an accumulation of material I is shown on the face I6 of theformation and penetrating into crevices I1 and into the intersticesbetween the sand particles of the formation I3. This 'accumulation ofparaffin I5 is also shown as inside of the casing II.

In one manner of practicing the method a body of water 2D has beendeposited in the well bore and any predetermined volume may be used,depending upon the amount of chemical which is to be used end, in actualpractice, it has been found that ur parts of water to one part oftreating material is satisfactory. The water may or may not lill thecavity I4 depending on the conditions encountered.

Fig. 2 shows the fabric'container of chemical 45 bei acid/ as havingbeen dropped into the well o we and moving downwardly therein. A body ofoil "I in any desired volume may have been depcsted upon the water 20either before the fabric container 4 is introduced or directlythereafter. 5 i either event this oil increased the static pressure onthe face of the' formation and tends to confine the mater, and will .beimore specifically described in connection with the operation of thereaction.

In Fig. 3 the fabric container 4 has landed on the bottom of the wellbore and has been ruptured. This breaking of the fabric containerexposes the caustic soda and the chemical or if container is notruptured in its fall, the fabric will absorb enough moisture to beginthe chemical reaction, and in this event, the fabric container will beeaten away, so that an exothermic reaction is initiated. This reactionraises the temperature of the water 20 to such an extent that steam isformed and with the static pressure on the face of the formation thisheat is caused to penetrate the paramn, asphalt, muck, or mud to beginmelting these deposits and disintegrating them as best seen in Fig. 3,where the particles of muck, or 7,0 mud and other accumulations 22 areshown as having been dislodged from the cavity. Some of the chemicalwhich has not yet reacted with the water is shown at the base of thecavity. y Naturally the reaction of the chemical caustic 15 soda andwater is violent and there is considerable agitation set up whichassists in dislodging the accumulation. The fact that heat is generatedincreases the temperature of the face of the formation and gasisliberated from the oil and the chemicals and from the accumulations onthe face of the formation and liner. The expansion of this gas causesthe breaking up of the cake on the face of the formation and assists indislodgment.

The tremendous heat generated sets up a convection Vcirculation so thatthe gas, water, steam and muck begin to rise in the well bore, as bestseen in Fig. 3. The heat of the reaction is confined to a considerableextent by the body of oil 2I on the top of the water and because of the'lighter specific gravity of the oil there is a tendency for it toremain on the top.

As the convection circulation is set up and the heated mixture rises inthe Wellbore it becomes intermixed with the oil due to the presence ofthe gas and steam which will move upwardly through the oil.

In addition to the heatand agitation created by the reaction there isalso a corrosive action which takes place. 'I'his corrosion of theshale, mud or muck dlsintegrates such material so that it is broken upinto smaller particles which will be readily carried along by themovement of the fluid in the well. Thus there are two forces tending todislodge the material.

This intermingling of the mixture and the oil forms an emulsion and ithas been found in practice that where a suflcient volume of oil has beenprovided the emulsion thus formed entraps the muck, paraffin andlmixture which rises in the well bore to form a composition from whichthe paraffin, asphalt, muck and mud will not recongeal. It appears thatportions of the gas formed are entrapped in the emulsion so that thesolid portions thereof are more or less frothy and foamy.

While these reactions and intermixing of the fluids, liquids and solidsis progressing naturally the heavier liquid will circulate toward thebottom of the well and cover the areas coated with the mud, muck, etc.Thus this hot cautic solution is in contact with the material to beremovediand the reactions continue automatically.

Fig. 4 shows a swab 30 as being lowered into the well bore whereby theemulsion just described can be removed from the well bore by washing theformation or liner by alternately applying vacuum and pressure to theformation.

This suction tends to dislodge additional material from the face of theformation and as the reaction of the remaining chemical at the bottomface of the cavity in Fig. 4. 'Ihe suction applied 'by the swab 30 orotherwise tends to draw this cake away from the formation.

Before the swabbing action additional water may be introduced into thewell bore, this water having a greater specific gravity than theemulsion, or the oil that remains in the upper reaches of the well borewill settle down into the cavity I4. In some instances the emulsionformed may be quite compact and the added waterrnight be held on topthereof instead of penetrating further into the well. To speed up thesettling of the water introduced into the well through the emulsionexisting in the well bore, a bailer may be run from the top of the well,through the water introduced and through the emulsion to the bottom ofthe well bore and then is pulled from the well. The water will tend tofollow the bailer thru the emulsion toward the bottom of the well. Thechemical and caustic soda. remaining in the bottom of the cavity will becaused to react upon the addition of water so as to initiate a second.reaction in which an additional amount of heat and corrosion is appliedto the formation. This second heating and corrosive reaction willpenetrate into the crevices such as I1 because of the fact that theinitial cake or emulsion I5 has been dislodged and also because of thefact that the face of the formation is now heated to a highertemperature. During this second reaction a swab may be lowered into thefluid of the well bore and a suction or reduction pressure createddepending upon the structure of the oil formation. This vacuum iscreated to pull all disintegrated accumulations into the well bore Sothat they may be carried up the well bore by the second reaction of thechemical. Pressure and suction may be alternately applied so as to surgethe hot chemical solution into and out of the formation.

In actual practice the heat and corrosive reaction lasts for a period ofthree or four hours. The swabbing action is carried on, during, or afterthis second reaction as circumstances may warrant.

Another manner of practicing the invention is to drop the fabriccontainer 4 of chemical and caustic soda into the well bore when it isentirely empty so that as it strikes the bottom of the cavity thechemical and caustic soda will be widely dispersed and will adhere tothe accumulation I5 on the face of the formation. Following thisdispersion the water and oil may be added. This method may be practicedthe same as previously described but the introduction of the `chemicalwhile the cavity or well isempty is sometimes of advantage, particularlywhen such well produces a quantity of water along with the oil. -A

A third body of water may be added to carry on a last reaction and toutilize every particle of chemical which has been introduced. It is hasbeen found that in practice satisfactory results can be obtained' if therst chemical reaction initiates a temperature of approximately 320 F.andk the second reaction at about 280 F., and the third reaction atabout 200 F. under low pressures. The well may be washed with water toremove any deposits of sand or undissolved shale which may have beendrawn into the cavity while swabbing, and then the tubing may be runback into the well and the'well is now ready to be pumpedafter havingbeen treated, unless swabbing the tubing to leave the well on a vacuumis thought necessary before placing the we'll on the pump.

It.will be apparent that three reactions have transpired, the rst tendsto heat and remove the exposed foreign material, the second continuesthe heat and corrosion on the formation and tends to carry thedisintegrated material upwardly in the well while the swabbing actioncreates alternate pressure and suction on the formation to surge the hotchemical solution into and out of the formation; the third reactionoccurs after enough water has been added to cover the 'face of theformation so that a hot caustic solution will be caused to penetrate theformation and wash out any remaining mud, muck, etc. The heaviersolution naturally floats out any emulsion remaining upwardly in thewell so that it may be readily removed. It has been found in actualpractice that if approximately one half of the total amount of water tobe used is introduced to begin with and then one quarter for the secondreaction and the nal one quarter for the third reaction that asatisfactory operation is obtained.

A composition for making up a charge to be used in treating wells mayconsist of: pounds of caustic soda, 25 pounds of aluminum dross; 121/2pounds of aluminum castings or sand; 15 pounds of soap powder, andsuiiicient oil to cover all of the particles constituting the charge.

Fig. 5 shows an arrangement wherein the tubing 40 is shown las beingpositioned in the well after the accumulation of muck and other materialhas been removed, as by swabbing or otherf wise.

A swab 30 of a suitable size is lowered thru the tubing and may be usedin this manner to create a suction on the face I4 of the formation. Astanding valve 4I is carried by the lower end of the tubing and in thismanner by an upward pull upon the swab 30. A reduction in pressure canbe created in the cavity I4 and the standing valve 4I will hold thispressure providing that the top of the well is sealed by the casingheadwhich is shown in the drawings. Annular chamber 43 between the tubingand the casing will also be subjected to this pressure in this form ofthe invention.

This reduction in pressure may be exerted on the formation so that therewill be a tendency to draw any water or chemical fluid from crevices ofthe formation, and the formation, and will also encourage the movementof oil and gas back into the well.

Fig. 6 shows an arrangement similar to Fig. 2 but wherein the wellcontains a liner 45 which has an upper blank section and the lowerperforated section 46. This liner carries an accumulation of muck I5both inside and outside thereof and this same accumulation is as shownon the face I4 of the well bore. A body of chemical and water has beendeposited inside of the liner 45 as indicated at 50 and a closure plug5I is in the form of a packer has been positioned in the casing I Iabove the liner. A lead seal or packer 52 forms a seal between the linerand the casing. At any time during the reaction a pull may be exertedonthe plug 5I to expand it and set it rmly.in the casing. The reactiongenerates pressure inside of the liner which pressure is thus confinedby the plug 5I so that the formation and equipment in the well bore willall be subjected to such pressure.

The pressure increases the eiciency of the chemical and corrosive so asto force the solution thru the strainer or liner and reacts against theformation. The plug 5I may be removed after the desired period of timeby an additional pull thereon so as to release they pressure andswabbing of the well will remove the accumulated emulsion and wash theliner of foreign material.

Fig. '7 shows a combination arrangement which is a combination of Figs.5 and 6 wherein the assembly of Fig. 5 has been inserted in the liner ofFig. 6. The operation will be obvious for exerting a reduction inpressure upon the formation after the muck has been cleaned therefrom,and this vacuum may be applied for any length of time and the alternatepressure and vacuum utilized until the muck has been dislodged andproduction of oil and gas initiated.

What is claimed is:

1. A method of treating oil wells to remove accumulations of parain,shale muck, rotary mud, etc. therefrom comprising depositing a charge ofaluminum and caustic in the well, adding a body of water in proportionto the amount of chemical and caustic, adding a body of oil to oat onthe water which oil is in proportion to the bottom hole pressure of thewell and intended to exert on the face of the formation a pressureslightly in excess of the formation pressure, heating the accumulationof material on the face of the formation by the heat generated from thereaction of the water, chemical and caustic, to dislodge the material bymelting and disintegrating and the formation of gas and steam due tosuch heating, so that such material will rise in the Well bore andbecome intimately mixed with the oil and water to form an emulsion ofthe material and oil Aand. water, and removing the emulsion thus formedfrom the well.

2. The method of treating wells to remove an accumulation of parafn orother materials from the face of the producing formation comprising thesteps of depositing a batch of heat forming chemical into the well boreat the elevation of the formation, depositing a body of water on top ofthe chemical so as to initiate a chemical reaction, providing a body ofoil on top of the water, allowing the chemical reaction of the water andchemical to proceed to form steam in the well bore so that theheatagitation and corrosive action will combine to melt and dislodge theparaflin from the face of the formation so that the increase in volumedue to such reaction and the formation of steam will institute acirculation of the melted paraffin which will move upwardly in the boreto intermix with the ,oil to form an emulsion, applying a suction on theformation face while removing the emulsion to break down the face of theformation, again adding water to prolong the chemical reaction in orderto continue the application of heat to the face of the formation to meltany parafnn remaining and subsequently applying suction andagainwithdrawing said additional emulsion which is formed.

3. A method of treating wells to remove accumulations of parailln,asphalt, mud or muck material which comprises the steps ofpredetermining the quantity of water necessary to react with apredetermined amount of chemical and caustic soda to create at a heatingand corrosive reaction of the necessary magnitude, introducing thechemical, caustic soda, and one half of the water into the well bore,introducing a body of oil on top thereof, allowing the reaction toproceed to soften, disintegrate and corrode the accumulation of materialin the well bore so that such material will be moved in the bore and anemulsion of the caustic solution, material and oil will be formed,adding one quarter of the water, so as to initiate a second reactionwith the chemical and acid remaining, removing the forming emulsionwhile alternately applying suction and pressure to the well bore, andnally adding the last quarter of water to complete the reaction andprovide a body of hot caustic solution in contact with the formationwhile alternately applying suction and pressure so as to surge suchsolution into and out of the formation to wash the formation ofaccumulated material, and continuing such surging and washing untilproduction occurs.

WALTER M. J ARRELL.

